At present, three-dimensional printers which run on various additive manufacturing technologies (e.g., the binder ejection technology, material extrusion technology, and liquid-tank photopolymerization technology) are on the market. Of these, three-dimensional printer systems running on the material extrusion technology (e.g., the system manufactured by Stratasys Inc., U.S.A.) are used for building a three-dimensional object layer-by-layer by extruding a flowable raw material from a nozzle part provided to an extrusion head, on the basis of a computer-aided design (CAD) model.
In a fused deposition modeling (hereinafter often referred to as FDM) method among such technologies, a raw material is first inserted, as a filament constituted of a thermoplastic resin, into an extrusion head and continuously extruded, while being fused, from the nozzle part provided to the extrusion head onto the X-Y plane within the chamber. The resin extruded is deposited on and fused to a resin deposit which has already been formed, then solidifies as the extruded resin cools, and is integrated therewith. The FDM method has come to be extensively used because this method is practiced by such a simple system.
In a three-dimensional printer running on the FDM method or the like, the extrusion step is usually repeated while the nozzle position relative to the platen rises in the Z-axis direction, which is perpendicular to the X-Y plane, thereby building a three-dimensional object akin to a CAD model (patent documents 1 and 2).
Hitherto, amorphous thermoplastic resins such as acrylonitrile/butadiene/styrene resins (hereinafter often referred to as “ABS resins”) or polylactic acid (hereinafter often referred to as “PLA resins”) have generally been used in preference as raw materials for the FDM method, from the standpoint of processability or flowability (patent documents 3 and 4).
Meanwhile, ABS resins or PLA resins generally are rigid materials, and there are hence cases where these resins cannot meet the requirements which are diversifying day by day. For example, in the case where a flexible three-dimensional object, such as the cover of a smartphone or the cap of a container, is desired to be formed, use of a soft resin as the material resin is desirable.
As soft resins for application to molding by three-dimensional printers, ones based on a thermoplastic urethane resin material (e.g., “NINJAFLEX (registered trademark)”, manufactured by FENNER DRIVES, Inc.) are on the market (non-patent document 1).